百里杜鹃风景名胜区季节性旅游影响分析

就百里杜鹃季节性旅游带来的各种影响进行分析,认为景区季节性旅游对景区生态环境、当地经济和社会文化都会产生影响,在此基础上,提出季节性旅游地的保护性开发建议。     

Estimating the production and mortality of fine roots in a Japanese cedar (Cryptomeria japonica D. Don) plantation using a minirhizotron technique

Fine roots are a key component of forested ecosystems, but available information is still limited. This study examined the production and mortality of fine roots less than 1 mm in diameter in a Japanese cedar (Cryptomeria japonica D. Don) plantation located on the Kanto Plain in central Japan. We used a minirhizotron technique in combination with soil coring, and collected data for 1 year (May 2002–May 2003). Fine root production and mortality were determined from changes in the lengths of individual fine roots on minirhizotron tubes. Both fine root production and mortality rates were greater in the upper soil than in lower soil levels. Both rates were seasonal, with higher values in summer than in winter; this trend was more pronounced in upper soil levels. These results suggest that environmental conditions, such as temperature or soil properties, affect the production and mortality rates of fine roots. Fine root production and mortality occurred simultaneously, and their rates were similar, which may have led to unclear seasonal changes in fine root standing crop estimates. Soil coring indicated that the fine root biomass of this stand was about 120 g m⁻², of which 40% was from Japanese cedar. The estimated rates of dry matter production and mortality of total fine roots, including understory plants, were both approximately 300 g m⁻² year⁻¹.     

How good are managed forests at conserving native woodpecker communities? A study in sub-Himalayan dipterocarp forests of northwest India

We assessed the impact of forest management on woodpecker community structure sub-Himalayan dipterocarp sal (Shorea robusta) forests. We selected eight sites representing four management-based ‘forest types’ (natural unworked sal, old- and young managed sal, and teak plantations). At each site, bird surveys were conducted along 2-km-long transects, 20 times during breeding and non-breeding seasons. Habitat characteristics were enumerated using circular and belt plots. Species composition across forest types was compared using multi-response permutation procedures. Indicator analysis identified woodpecker species preferring particular forest types. Biomass, abundance, and mean species richness of woodpeckers were highest in natural sal, intermediate in managed sal, and lowest in teak. There were apparent differences in woodpecker densities between seasons. Densities were higher in breeding season than non-breeding season for natural sal, while the opposite was true for managed sal. Woodpecker species composition significantly differed across forest types. The four largest species, including grey-headed (Picus canus) and greater yellownape (Picus flavinucha) that were identified as indicators, predominated natural sal but were scarce in other types. At a broader level, mean species richness of woodpeckers strongly indicated mean richness of other avifauna during breeding season. Our study suggests that forest management has significantly altered the sub-Himalayan woodpecker community structure. Managed sal forests, particularly teak plantations, are largely unable to support the original woodpecker assemblage during breeding season, although they provide foraging grounds during non-breeding season.     

Internal regulation of reproduction seasonality in earthworm Dendrobaena octaedra (Savigny, 1826) (Lumbricidae, Oligochaeta)

The study was conducted on Dendrobaena octaedra—a small epigeic earthworm species common in different forest types. In the laboratory the P (parent animals collected in forest) and F1 generations were cultured separately in containers filled with 50 g artificial soil. The containers were kept at 15±0.5 °C, 80% humidity and constant artificial light of low intensity. Every month during the 47 months of culture, the animals and cocoons were removed from the soil by washing on a sieve, weighed, and replaced into new soil. Individuals of the F1 generation did not reproduce continuously. Cocoon production was seasonal, despite culture in constant conditions throughout the whole experiment. Reproduction was highest in spring and summer, and dropped in the winter months. Seasonality characterized the fraction of animals reproducing as well as the number of cocoons produced. The observed seasonal changes in the cocoon production of the F1 generation cultured in constant conditions suggest that internal regulation of reproduction may exist in the earthworm D. octaedra. External factors like temperature, moisture, photoperiod or food supply, which could be responsible for seasonality of reproduction were missing.     

Seasonal effects on birth weight of lambs born to prolific ewes maintained under intensive management

Seasonal effects on birth weight (BWT) of lambs were studied in a prolific Assaf flock maintained under intensive management conditions with birth records of 7775 lambs distributed across all months in a period of 11 years. The average BWT was 4.21 kg. Month of the year had a significant (P < 0.001) effect on BWT, with the highest average BWT in April (4.6 kg) and the lowest average BWT in September (3.8 kg). The seasonal effect was noted for single lambs and lambs born in litters of 2 to 4 lambs. Gestation length, day length, rate of change in day length and heat load had significant (P < 0.001) effects on BWT. Day length during the early stage of gestation was inversely related to BWT while rate of changes in day length during the latter stages of gestation were directly associated with BWT.     

Climate and the epidemiology of gastrointestinal nematode infections of sheep in Europe

The free-living stages of gastrointestinal nematode parasites of sheep are strongly affected by climate. Thus, extreme heat and cold are detrimental to development and survival, while, within tolerable limits, increasing temperatures generally accelerate development but increase mortality. Moisture is needed for development and translation of larvae from faeces to pasture, and so rainfall is a limiting factor for transmission. Together, these factors underpin seasonal patterns of infection in sheep, as well as geographic variation in the epidemiology and relative importance of different species within Europe. Local knowledge and experience enable treatment to be targeted appropriately to prevent dangerous levels of infection. This traditional know-how can be supplemented by predictive epidemiological models, built on thorough understanding of the influence of climate on larval availability. However, management also has a dominant role in determining patterns of infection, and is itself influenced by climate. Current geographic variation in nematode epidemiology across Europe, and knowledge of systems from outside Europe, can provide only limited perspectives on the likely effects of climate change on disease in future. This is because disease arises from complex interaction between host and parasite factors, and the implementation of optimal control strategies to meet new challenges will be slowed by the inertia of current systems. Approaches to nematode control must therefore take account not only of parasite biology, but also the forces that shape sheep farming systems and management decisions.     

Post-thawing Sperm Quality in Chilean Purebred Stallions: Effect of Age and Seasonality

In this work, we investigated the influence of age and seasonality on sperm motility and DNA fragmentation in post-thawing semen from Chilean Purebred Stallions (CPS), a horse breed presenting the oldest genealogy record in South America with an interesting reproductive industry. Despite that semen from aged CPS is frozen all year round, there is a lack of studies characterizing the breed semen freezability in accordance with age and seasonality. Twenty fertile CPS were grouped into the young group, the middle group, and the aged group. Ten ejaculates from each stallion were obtained by using an artificial vagina during summer (December) and winter (July) and directly frozen. Subsequently, the frozen semen was thawed and analyzed by a computer-assisted semen analysis and flow cytometer assessing progressive motility, mean velocity, and DNA fragmentation spermatozoa. Kruskal–Wallis test and Pearson’s correlation were used to determine statistical differences among groups and correlation among variables (P ≤ .05). Both spermatozoa motility traits decreased progressively in accordance with age and seasonality, showing the lowest values in the aged group during winter and the highest values in the young group during summer. Deoxyribonucleic acid fragmentation increased significantly in accordance with age and seasonality being highest in the aged group during winter and lowest in the young group during summer. Post-thawing sperm quality showed a negative correlation with the age of the stallions and a positive correlation with the normal sperm morphology before freezing. These results allow the conclusion that age and seasonality are important factors that need to be considered during the selection of CPS for reproductive programs.     

Variation of serum inorganic phosphorus and association with haemoglobinuria and osteomalacia in female water buffaloes in Pakistan

Data from an animal health service in the Punjab of Pakistan showed that 39 adult female buffaloes with haemoglobinuria were 21 times more likely to have serum inorganic phosphorus (serum P) levels < 0.97 mmol/1 than 24 controls sampled during the period of case occurrence (December 1984–March 1985). Age > 7 years or early lactation (1–60 days post partum) were unrelated to the disease. Similarly, symptoms of osteomalacia in 19 multiparous buffaloes were associated with low P (OR = 14.3) but not with age. Subsequently, a serum survey was carried out from February 1985 to July 1987 to investigate serum P variations with season and host factors. Data from 139 farms (426 adult female buffaloes, 468 lactations) indicated strong farm and seasonal effects on serum P. Serum P declined during the study period and was lowest during December–March 1985/1986 and again 1986/1987. Calving season, parity > 1, high pregnancy > 6 months, or daily milk production were not related to serum P in the final model. Seasonal effects were interpreted as soil borne and related to feed changes from maize to berseem in December.     

羊草种群的水分利用动态

采用中子水分探测仪、光电叶面积仪和LI-1600型稳态气孔计对羊草草原的水分利用进行野外实验观测。结果表明,羊草种群蒸腾速率T(t)的季节变化主要取决于20-40cm土层贮水量(SW46),光合有效辐射(FAR)和大气日均温(AT)的影响,其中20-40cm土层贮水量对羊草蒸腾速率的季节变化影响最大。羊草蒸腾耗水量的季节动态归根结底受控于大气降水的时空分布,并在时间上滞后于大气降水一旬左右。羊草的水分利用率,主要受植物生长大周期的控制。生物量在前期积累较快,相应的水分利用率高,而后期增长缓慢,水分利用率低。